Showing papers on "Rectifier published in 1974"

Metal base cookware induction heating apparatus having improved power control circuit for insuring safe operation

Abstract: A metal based cookware induction heating apparatus having an improved power supply and control circuit comprised of a chopper inverter including a gate controlled power thyristor coupled to and supplying an induction heating coil with periodic energization currents. A full wave rectifier supplies rectified, unfiltered, unidirectional high voltage excitation potential to the chopper inverter which converts the excitation potential to a comparatively high frequency of the order of 20 kilohertz for supply to the induction heating coil. A gating circuit is provided for driving the chopper inverter directly from the rectified high voltage excitation potential supplied by the rectifier.

Low cast chopper inverter power supply and gating circuit therefor

Abstract: A metal based cookware induction heating apparatus having an improved power supply and control circuit comprised of a chopper inverter including a gate controlled power thyristor coupled to and supplying an induction heating coil with periodic energization currents. A full wave rectifier supplies rectified, unfiltered, unidirectional high voltage excitation potential to the chopper inverter which converts the excitation potential to a comparatively high frequency of the order of 20 kilohertz for supply to the induction heating coil. A gating circuit is provided for driving the chopper inverter directly from the rectified high voltage excitation potential supplied by the rectifier. The gating circuit includes an additional low voltage, direct current excitation potential connected to supply to a timing circuit charging capacitor. A voltage responsive switch such as a SUS or PUT or their equivalents is rendered conductive upon the timing circuit reaching a present value and in turn rendered conductive a constant current high voltage switching transistor connected in series with the primary winding of a pulse transformer across the output of the additional low voltage derived from the main full wave rectifier. The pulse transformer in turn has its secondary winding connected to the control gate of the power thyristor included in the chopper inverter.

Direct current arc power supply

Abstract: An arc power supply system having a three phase transformer and a rectifier which includes silicon controlled rectifiers. A feedback control system sums (1) a reference setpoint signal, (2) an adjustable voltage feedback signal, (3) an adjustable current feedback signal and (4) a series of pulses from a pulse generator. To provide overcurrent protection, the current feedback is compared with a reference to deactivate the supply system when the current feedback is greater than the reference for a predetermined duration of time. Further, start means compares the current feedback with a start reference upon start up to produce a value of direct current different from a normal value direct current. Further protection is provided from adverse effect of interference from switching surges, lightning, load surges and other interference generating equipment.

Current-supply arrangement for an electronic remote control receiver

Abstract: A current supply arrangement for an electronic remote control receiver, wherein a series circuit comprising a protective impedance, a capacitor and a full-wave rectifier is connected between two input terminals intended for connection to an alternating current network, a voltage limiter is operatively associated with the full-wave rectifier.

A.C. power supply circuit in combination with an A.C. source and a D.C. source

Abstract: An A.C. power supply circuit for use with an A.C. source and a battery includes a full-wave rectifier for rectifying the A.C. signal produced by the A.C. source, a battery supply control circuit responsive to a control signal for coupling the battery to the output of the rectifier, an A.C. sensing circuit for applying a control signal to the battery supply control circuit if the amplitude of the signal produced by the A.C. source falls below a predetermined level, and an oscillator circuit for producing an oscillatory signal in response to the signal present on the output of the rectifier. A battery sensing circuit is also included for producing a second control signal if the charge on the battery falls below some predetermined level. In response to this second control signal, a battery charge circuit applies a rectified A.C. signal from the A.C. source to the battery. If the charge on the battery falls below a second lower predetermined level, a shutdown circuit applies a signal to the battery supply control circuit to prevent the control circuit from connecting the battery to the output of the rectifier.

Regulated power supply with start-up and protective circuits

Abstract: A regulated silicon-controlled rectifier power supply for producing the direct current power for a television receiver is disclosed. The power supply is regulated by a shunt regulator, and the firing of the silicon-controlled rectifiers is controlled by a diac and timing capacitor coupled with the output of the shunt regulator. Spurious operation of the diac is prevented by a trigger clamp circuit which is reset at the beginning of each half-cycle of the input alternating current waveform to permit the diac to fire once during each half-cycle to initiate conduction of the appropriate silicon-controlled rectifier. In addition, a provision is made for insuring initial start-up of the operation of the power supply by use of an auxiliary power supply effective when the alternating current input signal first is applied to the system. Finally, a protective circuit is provided to shut down the power supply circuit in the event of an overvoltage condition.

Dc arc welding apparatus by high-frequency pulse current

Abstract: A DC arc welding apparatus using a high-frequency pulse current is disclosed and includes a rectifier bridge for commutating AC voltage and for applying DC voltage having a substantially smooth waveform to a circuit including an electrode and a workpiece for welding. A first switch is connected between an arc load formed between the electrode and the workpiece and a positive output side of the rectifier bridge. A second switch is connected between the arc load and a negative output side of the rectifier bridge. A capacitor has one end connected to a contact of the rectifier bridge and the first switch and another end connected to a contact of the rectifier bridge and the second switch. First and second rectifiers are connected so as to charge energy accumulated in the inductance of the circuit including the electrode and the workpiece during the off state of the first and second switches to the capacitor so that the current passed through the arc load is controlled by an on-off control of the first and second switches.

Self-powered thyristor trigger circuit

Abstract: A power control circuit includes first and second triacs each having a pair of load terminals connected across a pair of alternating current supply terminals in series with an individually associated winding of a split phase capacitor alternating current motor, and control circuit means for providing a unidirectional gating potential for said triacs in a low-loss non-heat producing or power dissipating manner comprising a filter capacitor having a first terminal connected to the junction of one of the supply terminals a load terminal of each of said triacs, said filter capacitor having a second terminal connected to the other power supply terminals by first and second circuits each of which circuits include a current limiting capacitor and a rectifier, and switching means selectively operable to apply said potential to the control gate of one or the other of said triacs.

Overcurrent relay circuit

Abstract: A solid-state relay circuit, which is not subject to falsetriggering on transients, for switching alternating current at selected current values is herein disclosed The solid-state relay circuit includes a current transformer for receiving a sensed alternating current and a full-wave rectifier bridge and filter connected to the current transformer for converting the sensed alternating current to a DC signal proportional to the sensed alternating current A pair of switching transistors (controlled by the DC signal) is connected to the rectifier bridge and filter, and also to a triac having two main terminals and a gate The switching transistors are connected between one main terminal and the gate of the triac A resistance-capacitance network is connected between the gate and the other main terminal of the triac The main terminals of the triac are also connected via output circuitry to an alternating current to be controlled When alternating current is present across the main terminals of the triac, the resistance-capacitance network conducts turn-off transients to the gate, automatically holding the triac conducting by refiring the triac at alternating current zero crossings as long as the switching transistors are OFF When the switching transistors turn ON, the turn-off transients are conducted away from the gate to the first main terminal of the triac, switching the triac non-conducting

Thyristor Control of Resistive and Series DC Motor Loads Using Integral-Cycle Switching

Abstract: The use of integral-cycle conduction of power appears to be useful for resistive load control, especially in heating applications. Uniform control sensitivity may be obtained over the whole power range if the controller has a fixed ON plus OFF time with variable ON/OFF ratio. The incremental load power controllable is proportional to the number of ON plus OFF supply cycles constituting a control period. Rectifier integral-cycle pulses of current were obtained from a single-phase supply using a pair of inverse-parallel connected thyristors and a diode bridge. This particular form of pulsewidth modulation was used for speed control of a fractional horsepower series dc motor on both open loop and closed loop. Steady-state characteristics in terms of mean current and mean speed were identical with those obtained from conventional dc supply. For high-speed low-torque operation there was little speed ripple and smooth, quiet motor performance was obtained. To obtain low speeds, the ON/OFF mark space ratio of the current was less than unity and the intermittent conduction caused speed ripple with motor noise and vibration.

Recent Progress in Power Reception Efficiency in a Free-Space Microwave Power Transmission System

Abstract: Recent improvements in rectifier devices in the form of specially designed GaAs Schottky-barrier diodes have been combined with rectifier circuit technology to produce receiving elements complete with low pass filtering at the microwave input and filtering at the output that operate in the 82-86 percent efficiency region. The combining of these elements in a rectenna array should produce an overall collection and rectification efficiency of over 80 percent.

Short HVDC transmission system with power factor control

Abstract: A method and apparatus for regulation of the power factor of a 3-phase network fed with power from another 3-phase network via a short high-voltage direct current transmission link interconnecting the two networks. The d.c. transmission link includes rectifier and inverter stations connected at opposite ends of the link and the inverter station is controlled in such manner as to supply power to the fed network at a variable leading power factor in dependence upon the actual power factor of the fed network.

Control process for operating a parallel-resonant circuit inverter that supplies an inductive charge, as well as the parallel-resonant circuit inverter operated by this method

Abstract: An improved parallel-resonant circuit inverter of the type having a rectifier, a thyristor DC/AC converter connected thereto and operating at a controllable frequency, a parallel resonant circuit with an inductive load and a method of operation of such circuit whereby the converter voltage U is maintained at a constant operating value UB for a constant DC current Ig = Igo, in a first control range characterized by a low resonant-circuit damping, and control of the direct current Ig for the purpose of maintaining the DC/AC voltage constant at its operating value UB, in the case of a constant thyristor extinction time tL = tLO, in a second control range characterized by a high damping, as well as by transition from the first to the second control range, if tL becomes equal to tLO in the case of increasing resonant-circuit damping, and transition from the second to the first control range, if Ig become equal to Igo in the case of decreasing damping.

Defibrillator testing device

Abstract: The tester does not require any external power source as it derives its energy from the pulse being measured. It includes circuitry which produces a signal proportional to the energy without directly calculating the energy. This is accomplished by generating a current portional to E 2 with a diode network and then integrating the current in a capacitor thus indirectly measuring the true energy. The results are read directly upon a linear meter or can be connected to an oscilloscope or the like for inspection or recording. A bridge rectifier can be used so that the circuit is responsive to both polarities of input pulse or it can be made responsive only to the unipolar signal.

Modelling of controlled rectifiers in feedback systems

Abstract: Controlled rectifiers are often incorporated in closed-loop systems. To determine the small signal performance of such systems the rectifier must be appropriately modelled. The paper reviews the existing models and compares their step response performance, Nyquist plots and stability boundaries. It is shown that a recently developed discrete model that takes into account the commutation angle is in good agreement with experimental results. The rectifier transfer function is obtained and the large signal non-linear behaviour discussed. A rigorous mathematical dynamic model developed is capable of describing both the small and the large signal response of the system.

Audio actuated lamp

Abstract: A system for electrically energizing a load, such as a lamp, upon receipt of an acoustic signal having predetermined characteristics, the system comprising a connector for an alternating current power source, acoustic pick-up, and a triggering device for supplying alternating current to the load. The improvement comprises a rectifier for providing a direct current output to be used by the control portion of the system, an amplifier for amplifying the output of the acoustic pick-up, and a time delay circuit for establishing a time period throughout the length of which the signal from the pick-up must exist in order to energize the load. The time delay circuit may include circuit components for activating the triggering device to supply alternating current to the load when such a predetermined signal is received for such a predetermined time duration. My system may also include a light detector for providing an electrical output controlling either the amplifier or the time delay circuit such that the load will be energized only when there is a combination of such a predetermined acoustic signal and an established light condition.

Ignition system for internal-combustion engines having timing stabilizing means

Abstract: Ignition in a six-cylinder internal combustion engine is supplied by a pair of similar alternator-driven, alternate-firing, capacitor discharge ignition systems, each discharged to the several spar k plugs of its own three cylinders by individual controlled rectifiers. A common trigger pulse generator is magnetically coupled to the engine flywheel and includes three individual trigger coils for generating properly referenced and angularly spaced pulses, each coil producing alternating positive and negative polarity pulses. A steering diode network connects one end of each triggering coil to a related controlled rectifier for an associated spark plug in one cylinder group and the opposite end of each coil to the controlled rectifier for a spark plug in the second cylinder group. Each ignition system includes a bias capacitor connected in series with the output of the three triggering coils to maintain an essentially constant ignition angle relative to trigger coil position over a wide range of engine speeds, and to establish back bias on each controlled rectifier gate-to-cathode junction during the intervals between trigger pulses. A pair of series connected resistors is connected in parallel with the bias capacitor with the center node supplying only a portion of the bias capacitor voltage to the gate to cathode junction of the related controlled rectifier in the absence of the triggering pulse. For a three cylinder engine a single one of the ignition systems is employed, and uses a wye-connection of the trigger coils in the trigger generator, the neutral wire being brought out and connected to the bias capacitor.

Variable frequency power converter for ac motor drive

Abstract: In a variable frequency power converter of a current type for driving an AC motor including a rectifier, an inverter, and a smoothing reactor disposed on a DC transmission line between the rectifier and the inverter, there are provided a series circuit having a switching circuit and a smoothing capacitor on the DC input side of the inverter and a feedback circuit having controlled rectifier elements and commutation reactors for feeding back the reactive power of the AC motor. The power converter operates as a current type converter until the output frequency of the converter reaches a predetermined value under the condition that the switching circuit and the controlled rectifier elements are non-conductive, and operates as a voltage type converter when the output frequency has reached the predetermined value under the condition that the switching circuit and the controlled rectifier elements are conductive.

Ballast circuits for discharge lamps

Abstract: A ballast circuit for a discharge lamp is arranged to supply a uni-directional voltage to the lamp which is made up of at least two current components which differ in phase. Flicker at the supply frequency f and at 2f is thus much reduced. A preferred ballast for use with a three-phase supply employs ballast capacitors in each of the three supply lines connected to a three-phase bridge rectifier, the output of which is applied to the lamp. A preferred ballast for use with a single phase supply includes a ballast capacitor and a ballast inductor connected through respective bridge rectifiers which have some components in common.

Wave Factors for Rectifiers with Capacitor Input Filters, and Other High Crest-Factor Loads

Abstract: Conventional, capacitor-input-filtered, full-wave rectifier power supplies draw much higher peak and rms line currents than the supply power drains would imply if the loads were resistive. Effective multiplication factors?termed wave factors?range from 5 to 15 for peak, and from 2 to 3 for rms, while remaining between 0.7 and 1 for average. Experimental data verify theoretical calculations for the wave factors involved. Ordinary clip-on and other conventional ammeters, measuring average but calibrated to read in rms for an equivalent sine wave, are thus unable to account for the difficulties sometimes encountered in the field. These include apparently undersized fuses, breakers and lines, plus severe clipping of the line voltage wave at the load. Solutions include use of auxiliary line inductors, plus wider recognition of the need for true rms metering with adequate crest factor capability in making all line current measurements. Implicacations for UPS (Uninterruptible Power Supply) manufacturers and users are also discussed. Wave factor WF is defined as the ratio of actual current drawn, to that which would be drawn by a resistive load with the same power consumption. Wave factors are derived for peak, rms and average input currents to full-wave rectifiers with capacitor input filters.

Polyphase rectifier system for providing two output current-voltage ranges

Abstract: A polyphase rectifier system which provides two output current-voltage ranges upon the system direct current output circuitry. Each phase of a polyphase potential source is rectified by a respective rectifier circuit having the alternating current input circuit thereof electrically connected to the output electrical coil of the corresponding phase of the polyphase potential source and the direct current output circuit thereof connected in parallel with the direct current output circuit of all of the other rectifier circuits. An electrical switching means operable to the electrical circuit open and closed conditions is provided for electrically interconnecting one terminal end of all of the output electrical coils of the polyphase potential source when operated to the electrical circuit closed condition.

Open screen smoke detector and circuit

Abstract: Herein disclosed is a particularly sensitive smoke detector system featuring a solid state sensor having a wide-mesh screen and employing a warning device in circuit with the anode-cathode path of a silicon control rectifier and an alternating current source. A biasing circuit comprising the solid state sensor is utilized to sense the presence of smoke and to cause the rectifier to pass current and to actuate the warning device when the threshold of the silicon control rectifier is exceeded.

Ground connection monitoring apparatus for mobile machines

Abstract: Apparatus protected against ground faults for monitoring the ground connection between a grounded power source and a mobile machine provided with multi-phase power through a multi-conductor trailing cable has a star arrangement of impedances connected to the phase conductors at the power source and a like arrangement connected at the machine, the junctions of which are connected to the ground conductor at each end, through a silicon-controlled rectifier device which is paralleled by a monitoring impedance. At least one impedance of one of the star arrangement of impedances is adjusted to provide a low monitoring voltage which circulates a current through the ground conductor and monitoring impedance. The voltage across the latter actuates monitoring means. The silicon-controlled rectifier is adjusted to conduct when the voltage across it rises above the monitoring level. The monitoring current may be alternating current, or direct current obtained from a rectifier in circuit with the ground conductor.

Frequency regulating device for A.C. systems interconnected through D.C. systems

Abstract: In a system interconnection composed of two a.c. systems, two converters connected with the respective a.c. systems and a d.c. power transmission system, one of the converters or rectifier is subject to constant current control and the other or inverter is subject to constant margin angle control. In the control system, the difference between the frequencies of the a.c. systems to which the respective converters are connected is utilized for modifying the set point of control. The greater the frequency difference, the rate of modification of the set point is increased so as to minimize the frequency difference between the a.c. systems remaining after control.

Arrangement for protection of self-controlled inverter fed from an intermediate d.c. voltage link

Abstract: A self-controlled polyphase bridge type inverter utilizes controllable valves of the semi-conductor type such as thyristors in the branches of the bridge, the bridge being fed from the output of a rectifier by way of an intermediate d.c. voltage link circuit that includes at least one smoothing condenser and at least one smoothing inductance. In the event of a through-going ignition i.e. a mal-function in the inverter all controllable valves of the inverter including load valves and/or any auxiliary valves are activated simultaneously by an ignition pulse so that the smoothing condenser together with such inductances as are included in the inverter form an oscillating circuit while the valves are simultaneously ignited. In order to protect the inverter structure under such a condition, a diode in series with a resistor is connected electrically in parallel with the smoothing condenser, the diode being wired in the blocking direction relative to the normal polarity of the d.c. voltage link circuit and providing an electrically conductive connection between the poles of the smoothing condenser after the change in polarity of the condenser caused by the oscillation process beginning with the second half-cycle of the voltage.

Control system for brushless motor

Abstract: A control system for a brushless motor is disclosed which comprises an AC power supply, a rectifier circuit including controlled rectifier elements for converting the alternating current supplied by the AC power supply into a direct current, an inverter circuit including controlled rectifier elements for converting the direct current produced by the rectifier circuit into an alternating current, a motor driven by the inverter circuit and a position detector for detecting a signal representing rotational positions of the motor. The controlled rectifier elements of the inverter circuit are fired in predetermined sequence in response to detection signals from the position detector, while the DC output current of the rectifier is continually controlled at each commutation of the inverter circuit at low motor speeds. A predetermined number of signals in synchronism with each commutation of the inverter circuit are included in one cycle, so that the DC output current of the rectifier circuit is controlled for continual operation by the use of signals with different delay times behind the aforementioned signals concurrent with the commutation of the inverter.

Over-voltage protection circuit

Abstract: An over-voltage protection circuit for an electric generating machine having a controlled rectifier for shunting the output winding of the machine in the event of an over-voltage condition includes impedance means connected in series with the controlled rectifier and regulation circuitry responsive to current flowing through the impedance means for preventing the excitation of the field when the controlled rectifier is conductive. An improved triggering circuit including a Zener diode and a transistor switch is employed to assure proper triggering of the controlled rectifier.

High voltage protection circuit

Abstract: An integrated thyristor-rectifier (ITR) replaces the conventional damper diode in a television deflection system The damper diode function is performed by the rectifier portion of the ITR, the thyristor being reverse biased during the damping interval The forward breakover voltage characteristic of the thyristor portion of the ITR insures that the cathode of the damper-rectifier portion of the ITR will not rise to a higher voltage than the thyristor''s forward breakover voltage above the cathode of the thyristor during the remaining portion of the deflection cycle If the cathode of the damper-rectifier rises above the thyristor forward breakover voltage, the thyristor begins to conduct heavily causing the deflection current to decay rapidly and rendering the television display unviewable while simultaneously limiting the generated high voltage

Transportation system with brake control and combined brake and field power supply

Abstract: A solid-state static power converter receives a three-phase A.C. input and directly supplies direct current to a D.C. motor armature circuit to operate a traction sheave to control the movement of an elevator car in response to an error signal derived by the selective summation of a speed signal from a tachometer and a vehicle speed command signal. A combined solidstate static power converter receives the three-phase A.C. input and directly supplies direct current to a field circuit of the D.C. motor in response to the operation of a field gating control circuit and also directly supplies direct current to a brake operating solenoid circuit controlling a friction braking element selectively coupled to an output shaft of the D.C. motor. The combined field and brake static power converter includes three controlled rectifying devices and three diodes connected to selectively supply half-wave rectified uni-directional power to the field circuit while a fourth controlled rectifier is connected to one of the phases and cooperates with one or more of the diodes utilized in the field current conversion together with one field output lead to supply uni-directional energy to the brake solenoid. The brake gating control includes a summing circuit receiving an alternating phase reference signal from the source through a lag filter circuit, a disable signal from the source through lead and lag filtering circuits, a constant reference signal, and a brake energy command signal supplied from a second summing circuit. The second summing circuit receives a brake lifting command signal in response to the supervisory control and a brake energy sensed feedback signal.

Arrangement for controlling a thyristor

Abstract: In a control arrangement for a thyristor, a storage capacitor is coupled, through a rectifier, in parallel with the thyristor, with a firing capacitor, a choke and an auxiliary thyristor coupled in parallel across the storage capacitor and means provided to couple the voltage of the firing capacitor to the control electrode of the thyristor. The energy for controlling the thyristor is taken from the reverse thyristor voltage and the control signal for firing is provided at low power such as through an optically transmission.